(CNN) -- Guatemalan authorities have issued arrest warrants for two prominent brothers in connection with last year's slaying of a lawyer who left behind a videotape saying President Alvaro Colom would be responsible if anything happened to him, the suspects' attorney confirmed Wednesday.

The brothers, who own a pharmaceutical company, are in hiding, said their lawyer, Alexis Calderon. He added that he does not know where they are.

Calderon denies that his clients, who have not been charged, were involved in the slaying. Under Guatemalan law, arrest warrants can be issued without charges being filed.

He said authorities "won't find a motive. This is a story being made up to implicate people who didn't have anything to do with it."

The arrest warrants were issued December 9, Calderon said. The nation's attorney general's office and other officials have declined to release information on why police are looking for the Valdez Paiz brothers.

Rosenberg was shot and killed in a daylight attack May 10 while riding his bicycle in Guatemala City, the nation's capital.

Eleven men have been arrested in the case. Three of them have testified about who ordered the assassination and what roles the suspects may have played, Guatemalan authorities have said.

According to a tape of one of the men's testimony published by the Prensa Libre, El Periodico and other Guatemalan newspapers last week, suspect Jesus Manuel Cardona Medina said the Valdez Paiz brothers commissioned the slaying. Cardona Medina testified that Rosenberg asked his cousins to find an assassin to kill someone who was blackmailing him, the news reports said.

The newspapers said Cardona testified that the brothers did not know the identity of the person who was being targeted and learned it was Rosenberg only after he had been killed. That purported scenario means Rosenberg would have arranged his own death.

CNN has not heard the tape nor independently confirmed its contents. Calderon, the lawyer for the Valdez Paiz brothers, said he has not heard the tape either.

The judge in the case, Veronica Galicia, said her job prevents her from commenting on whether the newspaper account of the testimony is correct. But she indicated that a tape of the hearing existed, saying that she walked into the courtroom in which the suspects were giving pretrial testimony and saw a man standing on a chair outside an open window and holding a microphone inside the room.

Galicia said she called security and the person fled. Galicia said she did not get a good look at the person and could not identify him.

The day after the slaying, the videotape in which Rosenberg blamed Colom became public. He recorded the tape three days before his death.

Rosenberg said Colom wanted him dead because the lawyer had been blaming the president and some of his top associates for the slayings of a prominent businessman and his daughter the previous month. Businessman Khalid Musa and his daughter were killed, Rosenberg said, because they had refused to participate in acts of corruption as the president wanted.

Rosenberg legally represented Musa.

Colom has repeatedly denied involvement with any of the slayings and has vowed to find the killers.

Mario David Garcia, a lawyer and radio show host who taped Rosenberg's accusation, said Rosenberg expressed concern for his safety.

"It's very hard to challenge your own government," Garcia said. "Rosenberg was a very serious lawyer. He didn't speculate."

Mario Gonzalez, manager of the business Musa owned, said in May that Rosenberg felt he was targeted.

"He felt threatened," Gonzalez said. "[But] he was not afraid. He had been threatened, but he knew that sooner or later, he would be killed. 'They are going to kill me,' he said."

The lawyer's niece, Mariela Rosenberg, said her uncle learned to accept his fate.

"He had many threats," she said shortly after the killing, "and when he saw it was inevitable, he taped a video."

Charges against the eight suspects, who have not cooperated with authorities, were lodged Wednesday. The other three suspects are scheduled to have a hearing this month.

The results of an investigation by a special United Nations commission are due to be released next week. The International Commission Against Impunity in Guatemala, established in 2006 to investigate corruption and political violence, has employed the services of investigators from 20 nations, spokesman Diego Alvarez said.

"The investigation has been very well staffed," he said. "It has been very complete, very scientific, very technological."

More than 200,000 people have been killed in Guatemala since 1970, mostly as a result of organized crime, drug-trade violence and a 36-year civil war that ended in 1996.

Galicia asked the commission for protection Tuesday. She said she has been concerned for her safety, particularly after one of her top court officials was gunned down on a street corner in October. The slaying of Merlington Marck Monzon remains unsolved.